Two New Indian Species of the little-known Genus Aulodrilus Bretscher of the Aquatic Oligochæta belonging to the Family Tubificidæ.


  • *Communicated by Dr. J. Stephenson


  • 1The diagnostic characters of the genus and the species are given.
  • 2The reproductive organs hitherto unknown are described in detail.
  • 3The prostate is large and massive; it opens into the atrium near the antero-ventral margin. The prostate cells soon after they are functional and filled with secretion lose their structure and become disorganized, while the secretion passes as an inwardly moving mass into the atrium at the point, where the gland is connected with it. The atrial epithelium also at this time undergoes a great change on account of the secretion by which its cells become replaced having lost their entity. The manner of connection of the prostate with the atrium suggests its origin as an outgrowth of the atrial epithelium.
  • 4The cælomic cavity in the segment which contains the spermathecæ is separated off from the peripheral portion by the formation of a ventro-lateral wall, which is composed of a central muscular layer surrounded on either side by a peculiar parenchymatous tissue of peritoneal origin. The central chamber thus formed contains a11 the organs of the segment and is also filled with the developing sperms; the spermathecal ducts pass through the ventro-lateral corners of the wall on their may to the exterior.
  • 5The spermathecæ are ectodermal in origin, and arise as an invagination from the epidermis.
  • 6As regards its systematic position Aulodrilus belongs to the Tubificidæ, although it resembles the Naididæ in some of its features. Among the Tubificidæ it is related to Tubifex and Psammorcytes on the one hand, and Branchiura and Kawamuria on the other. The spermiducal chamber, which is present in Monopylephorus, also seems to be independently derived in these genera, and perhaps acts as a sucker during copulation.